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  <div class="section" id="compatibility-functions">
<h1>Compatibility Functions<a class="headerlink" href="#compatibility-functions" title="Permalink to this headline">¶</a></h1>
<p>CodeIgniter provides a set of compatibility functions that enable
you to use functions what are otherwise natively available in PHP,
but only in higher versions or depending on a certain extension.</p>
<p>Being custom implementations, these functions will also have some
set of dependencies on their own, but are still useful if your
PHP setup doesn&#8217;t offer them natively.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Much like the <a class="reference internal" href="common_functions.html"><em>common functions</em></a>, the
compatibility functions are always available, as long as
their dependencies are met.</p>
</div>
<div class="contents local topic" id="contents">
<ul class="simple">
<li><a class="reference internal" href="#password-hashing" id="id7">Password Hashing</a><ul>
<li><a class="reference internal" href="#dependencies" id="id8">Dependencies</a></li>
<li><a class="reference internal" href="#constants" id="id9">Constants</a></li>
<li><a class="reference internal" href="#function-reference" id="id10">Function reference</a></li>
</ul>
</li>
<li><a class="reference internal" href="#hash-message-digest" id="id11">Hash (Message Digest)</a><ul>
<li><a class="reference internal" href="#id1" id="id12">Dependencies</a></li>
<li><a class="reference internal" href="#id2" id="id13">Function reference</a></li>
</ul>
</li>
<li><a class="reference internal" href="#multibyte-string" id="id14">Multibyte String</a><ul>
<li><a class="reference internal" href="#id3" id="id15">Dependencies</a></li>
<li><a class="reference internal" href="#id4" id="id16">Function reference</a></li>
</ul>
</li>
<li><a class="reference internal" href="#standard-functions" id="id17">Standard Functions</a><ul>
<li><a class="reference internal" href="#id5" id="id18">Dependencies</a></li>
<li><a class="reference internal" href="#id6" id="id19">Function reference</a></li>
</ul>
</li>
</ul>
</div>
<div class="custom-index container"></div><div class="section" id="password-hashing">
<h2><a class="toc-backref" href="#id7">Password Hashing</a><a class="headerlink" href="#password-hashing" title="Permalink to this headline">¶</a></h2>
<p>This set of compatibility functions offers a &#8220;backport&#8221; of PHP&#8217;s
standard <a class="reference external" href="http://php.net/password">Password Hashing extension</a>
that is otherwise available only since PHP 5.5.</p>
<div class="section" id="dependencies">
<h3><a class="toc-backref" href="#id8">Dependencies</a><a class="headerlink" href="#dependencies" title="Permalink to this headline">¶</a></h3>
<ul class="simple">
<li>PHP 5.3.7</li>
<li><tt class="docutils literal"><span class="pre">CRYPT_BLOWFISH</span></tt> support for <tt class="docutils literal"><span class="pre">crypt()</span></tt></li>
</ul>
</div>
<div class="section" id="constants">
<h3><a class="toc-backref" href="#id9">Constants</a><a class="headerlink" href="#constants" title="Permalink to this headline">¶</a></h3>
<ul class="simple">
<li><tt class="docutils literal"><span class="pre">PASSWORD_BCRYPT</span></tt></li>
<li><tt class="docutils literal"><span class="pre">PASSWORD_DEFAULT</span></tt></li>
</ul>
</div>
<div class="section" id="function-reference">
<h3><a class="toc-backref" href="#id10">Function reference</a><a class="headerlink" href="#function-reference" title="Permalink to this headline">¶</a></h3>
<dl class="function">
<dt id="password_get_info">
<tt class="descname">password_get_info</tt><big>(</big><em>$hash</em><big>)</big><a class="headerlink" href="#password_get_info" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$hash</strong> (<em>string</em>) &#8211; Password hash</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Information about the hashed password</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">array</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/password_get_info">PHP manual for
password_get_info()</a>.</p>
</dd></dl>

<dl class="function">
<dt id="password_hash">
<tt class="descname">password_hash</tt><big>(</big><em>$password</em>, <em>$algo</em><span class="optional">[</span>, <em>$options = array()</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#password_hash" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$password</strong> (<em>string</em>) &#8211; Plain-text password</li>
<li><strong>$algo</strong> (<em>int</em>) &#8211; Hashing algorithm</li>
<li><strong>$options</strong> (<em>array</em>) &#8211; Hashing options</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Hashed password or FALSE on failure</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/password_hash">PHP manual for
password_hash()</a>.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Unless you provide your own (and valid) salt, this function
has a further dependency on an available CSPRNG source. Each
of the following would satisfy that:
- <tt class="docutils literal"><span class="pre">mcrypt_create_iv()</span></tt> with <tt class="docutils literal"><span class="pre">MCRYPT_DEV_URANDOM</span></tt>
- <tt class="docutils literal"><span class="pre">openssl_random_pseudo_bytes()</span></tt>
- /dev/arandom
- /dev/urandom</p>
</div>
</dd></dl>

<dl class="function">
<dt id="password_needs_rehash">
<tt class="descname">password_needs_rehash</tt><big>(</big><big>)</big><a class="headerlink" href="#password_needs_rehash" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$hash</strong> (<em>string</em>) &#8211; Password hash</li>
<li><strong>$algo</strong> (<em>int</em>) &#8211; Hashing algorithm</li>
<li><strong>$options</strong> (<em>array</em>) &#8211; Hashing options</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">TRUE if the hash should be rehashed to match the given algorithm and options, FALSE otherwise</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">bool</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/password_needs_rehash">PHP manual for
password_needs_rehash()</a>.</p>
</dd></dl>

<dl class="function">
<dt id="password_verify">
<tt class="descname">password_verify</tt><big>(</big><em>$password</em>, <em>$hash</em><big>)</big><a class="headerlink" href="#password_verify" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$password</strong> (<em>string</em>) &#8211; Plain-text password</li>
<li><strong>$hash</strong> (<em>string</em>) &#8211; Password hash</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">TRUE if the password matches the hash, FALSE if not</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">bool</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/password_verify">PHP manual for
password_verify()</a>.</p>
</dd></dl>

</div>
</div>
<div class="section" id="hash-message-digest">
<h2><a class="toc-backref" href="#id11">Hash (Message Digest)</a><a class="headerlink" href="#hash-message-digest" title="Permalink to this headline">¶</a></h2>
<p>This compatibility layer contains backports for the <tt class="docutils literal"><span class="pre">hash_equals()</span></tt>
and <tt class="docutils literal"><span class="pre">hash_pbkdf2()</span></tt> functions, which otherwise require PHP 5.6 and/or
PHP 5.5 respectively.</p>
<div class="section" id="id1">
<h3><a class="toc-backref" href="#id12">Dependencies</a><a class="headerlink" href="#id1" title="Permalink to this headline">¶</a></h3>
<ul class="simple">
<li>None</li>
</ul>
</div>
<div class="section" id="id2">
<h3><a class="toc-backref" href="#id13">Function reference</a><a class="headerlink" href="#id2" title="Permalink to this headline">¶</a></h3>
<dl class="function">
<dt id="hash_equals">
<tt class="descname">hash_equals</tt><big>(</big><em>$known_string</em>, <em>$user_string</em><big>)</big><a class="headerlink" href="#hash_equals" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$known_string</strong> (<em>string</em>) &#8211; Known string</li>
<li><strong>$user_string</strong> (<em>string</em>) &#8211; User-supplied string</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">TRUE if the strings match, FALSE otherwise</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/hash_equals">PHP manual for
hash_equals()</a>.</p>
</dd></dl>

<dl class="function">
<dt id="hash_pbkdf2">
<tt class="descname">hash_pbkdf2</tt><big>(</big><em>$algo</em>, <em>$password</em>, <em>$salt</em>, <em>$iterations</em><span class="optional">[</span>, <em>$length = 0</em><span class="optional">[</span>, <em>$raw_output = FALSE</em><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#hash_pbkdf2" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$algo</strong> (<em>string</em>) &#8211; Hashing algorithm</li>
<li><strong>$password</strong> (<em>string</em>) &#8211; Password</li>
<li><strong>$salt</strong> (<em>string</em>) &#8211; Hash salt</li>
<li><strong>$iterations</strong> (<em>int</em>) &#8211; Number of iterations to perform during derivation</li>
<li><strong>$length</strong> (<em>int</em>) &#8211; Output string length</li>
<li><strong>$raw_output</strong> (<em>bool</em>) &#8211; Whether to return raw binary data</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Password-derived key or FALSE on failure</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/hash_pbkdf2">PHP manual for
hash_pbkdf2()</a>.</p>
</dd></dl>

</div>
</div>
<div class="section" id="multibyte-string">
<h2><a class="toc-backref" href="#id14">Multibyte String</a><a class="headerlink" href="#multibyte-string" title="Permalink to this headline">¶</a></h2>
<p>This set of compatibility functions offers limited support for PHP&#8217;s
<a class="reference external" href="http://php.net/mbstring">Multibyte String extension</a>. Because of
the limited alternative solutions, only a few functions are available.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">When a character set parameter is ommited,
<tt class="docutils literal"><span class="pre">$config['charset']</span></tt> will be used.</p>
</div>
<div class="section" id="id3">
<h3><a class="toc-backref" href="#id15">Dependencies</a><a class="headerlink" href="#id3" title="Permalink to this headline">¶</a></h3>
<ul class="simple">
<li><a class="reference external" href="http://php.net/iconv">iconv</a> extension</li>
</ul>
<div class="admonition important">
<p class="first admonition-title">Important</p>
<p class="last">This dependency is optional and these functions will
always be declared. If iconv is not available, they WILL
fall-back to their non-mbstring versions.</p>
</div>
<div class="admonition important">
<p class="first admonition-title">Important</p>
<p class="last">Where a character set is supplied, it must be
supported by iconv and in a format that it recognizes.</p>
</div>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">For you own dependency check on the actual mbstring
extension, use the <tt class="docutils literal"><span class="pre">MB_ENABLED</span></tt> constant.</p>
</div>
</div>
<div class="section" id="id4">
<h3><a class="toc-backref" href="#id16">Function reference</a><a class="headerlink" href="#id4" title="Permalink to this headline">¶</a></h3>
<dl class="function">
<dt id="mb_strlen">
<tt class="descname">mb_strlen</tt><big>(</big><em>$str</em><span class="optional">[</span>, <em>$encoding = NULL</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#mb_strlen" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$str</strong> (<em>string</em>) &#8211; Input string</li>
<li><strong>$encoding</strong> (<em>string</em>) &#8211; Character set</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Number of characters in the input string or FALSE on failure</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/mb_strlen">PHP manual for
mb_strlen()</a>.</p>
</dd></dl>

<dl class="function">
<dt id="mb_strpos">
<tt class="descname">mb_strpos</tt><big>(</big><em>$haystack</em>, <em>$needle</em><span class="optional">[</span>, <em>$offset = 0</em><span class="optional">[</span>, <em>$encoding = NULL</em><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#mb_strpos" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$haystack</strong> (<em>string</em>) &#8211; String to search in</li>
<li><strong>$needle</strong> (<em>string</em>) &#8211; Part of string to search for</li>
<li><strong>$offset</strong> (<em>int</em>) &#8211; Search offset</li>
<li><strong>$encoding</strong> (<em>string</em>) &#8211; Character set</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Numeric character position of where $needle was found or FALSE if not found</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">mixed</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/mb_strpos">PHP manual for
mb_strpos()</a>.</p>
</dd></dl>

<dl class="function">
<dt id="mb_substr">
<tt class="descname">mb_substr</tt><big>(</big><em>$str</em>, <em>$start</em><span class="optional">[</span>, <em>$length = NULL</em><span class="optional">[</span>, <em>$encoding = NULL</em><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#mb_substr" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$str</strong> (<em>string</em>) &#8211; Input string</li>
<li><strong>$start</strong> (<em>int</em>) &#8211; Position of first character</li>
<li><strong>$length</strong> (<em>int</em>) &#8211; Maximum number of characters</li>
<li><strong>$encoding</strong> (<em>string</em>) &#8211; Character set</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Portion of $str specified by $start and $length or FALSE on failure</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/mb_substr">PHP manual for
mb_substr()</a>.</p>
</dd></dl>

</div>
</div>
<div class="section" id="standard-functions">
<h2><a class="toc-backref" href="#id17">Standard Functions</a><a class="headerlink" href="#standard-functions" title="Permalink to this headline">¶</a></h2>
<p>This set of compatibility functions offers support for a few
standard functions in PHP that otherwise require a newer PHP version.</p>
<div class="section" id="id5">
<h3><a class="toc-backref" href="#id18">Dependencies</a><a class="headerlink" href="#id5" title="Permalink to this headline">¶</a></h3>
<ul class="simple">
<li>None</li>
</ul>
</div>
<div class="section" id="id6">
<h3><a class="toc-backref" href="#id19">Function reference</a><a class="headerlink" href="#id6" title="Permalink to this headline">¶</a></h3>
<dl class="function">
<dt id="array_column">
<tt class="descname">array_column</tt><big>(</big><em>array $array</em>, <em>$column_key</em><span class="optional">[</span>, <em>$index_key = NULL</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#array_column" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$array</strong> (<em>array</em>) &#8211; Array to fetch results from</li>
<li><strong>$column_key</strong> (<em>mixed</em>) &#8211; Key of the column to return values from</li>
<li><strong>$index_key</strong> (<em>mixed</em>) &#8211; Key to use for the returned values</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">An array of values representing a single column from the input array</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">array</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/array_column">PHP manual for
array_column()</a>.</p>
</dd></dl>

<dl class="function">
<dt id="hex2bin">
<tt class="descname">hex2bin</tt><big>(</big><em>$data</em><big>)</big><a class="headerlink" href="#hex2bin" title="Permalink to this definition">¶</a></dt>
<dd><table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>$data</strong> (<em>array</em>) &#8211; Hexadecimal representation of data</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">Binary representation of the given data</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">string</p>
</td>
</tr>
</tbody>
</table>
<p>For more information, please refer to the <a class="reference external" href="http://php.net/hex2bin">PHP manual for hex2bin()</a>.</p>
</dd></dl>

</div>
</div>
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